docs: def show_schemas(schemaname):
      """
      Show anchore document schemas.
      """
  
      ecode = 0
      try:
          schemas = {}
          schema_dir = os.path.join(contexts['anchore_config']['pkg_dir'], 'schemas')
          for f in os.listdir(schema_dir):
              sdata = {}
              try:
                  with open(os.path.join(schema_dir, f), 'r') as FH:
                      sdata = json.loads(FH.read())
              except:
                  anchore_print_err('found schema file but failed to parse: ' + os.path.join(schema_dir, f))
  
              if sdata and (not schemaname or f in schemaname):
                  schemas[f] = sdata
  
          if not schemas:
              anchore_print_err("no specified schemas were found to show")
          else:
              anchore_print(json.dumps(schemas, indent=4))
  
      except Exception as err:
          anchore_print_err('operation failed')
          ecode = 1
  
      sys.exit(ecode)